textproduct: Albany

WHAT HAS CHANGED

Lingering clouds tonight have kept temperatures milder than previous forecast in southern VT, the Taconics, and the Upper Hudson Valley. Therefore confidence in frost through this morning has decreased. Will continue to monitor trends and may need to cancel frost advisories early.

Lowered dew points for today given very deep mixing and breezy winds. Also slowed down the eastward progression of likely and categorical POPs Tuesday night into Wednesday morning as the best chance for more widespread rain holds off until Wednesday afternoon.

KEY MESSAGES

1) Moderate to high confidence in areas of frost and freezing temperatures tonight into early Tuesday morning where the growing season has begun except in the mid-Hudson Valley and NW CT.

2) Increasing confidence for periods of widespread rain and embedded thunderstorms Wednesday through Friday, with a low to medium chance for locally heavy rain.

DISCUSSION

KEY MESSAGE 1...

Temperatures tonight have been slow to decrease as we remain upstream of a trough positioned over Ontario with southwest flow maintaining clouds. As of 2 AM, temperatures are still mild in the low to mid 40s in the Upper Hudson Valley, southern VT and the northern Taconics. If clouds persist and temperature struggle to cool over the next hour or so, we likely will cancel the frost advisory early there. However, the Mohawk Valley, Schoharie County and Helderbergs are cooler in the mid to upper 30s given clearer skies so higher confidence in frost forming through sunrise.

After our trough axis pushes through eastern NY/western New England this evening, except subsidence and high pressure from the Great Lakes/southern Canada to build eastward. This will support clearing skies and weakening winds, especially after Midnight, from west to east. Ideal radiational cooling combined with an incoming cooler air mass will support chilly temperatures by early Tuesday morning. There is a 40 to 80% chance that temperatures will drop below 36 degrees in southern VT, western MA, the northern Taconics, Upper Hudson Valley, Mohawk Valley, Schoharie County, and the northern/eastern Catskills where the growing season has begun. Thus, confidence remains moderate to high that we will need frost advisories and even some freeze warnings. Clouds will hang on a little longer in the mid- Hudson Valley, southern Taconics and NW CT which should keep these areas milder and thus mitigate frost.

KEY MESSAGE 2...

Confidence continues to increase that a maturing sfc low will track from the Great Lakes into the Northeast on Wednesday resulting in an initial period of isentropic lift and overrunning rain showers with the steadiest rain focused along the south facing slopes of the southern Adirondacks and eastern Catskills due to upslope enhancements. As the parent trough amplifies and slowly shifts into the Northeast Wednesday night into Thursday, a secondary sfc low may develop along its cold front and slow down the progression of the rain. Latest ensembles continue to indicate moderate confidence for rain continuing into Thursday, especially near and east of the Hudson River where strong southerly winds will likely maintain the conveyor belt of warm air and moisture advection. As the parent trough moves overhead on Thursday, the cool pool aloft may even support sufficient instability resulting in embedded thunderstorms and potential for locally heavy rain. As noted in the previous discussion, trends continue to show the potential for the parent shortwave to close off Thursday into Friday, which would further slow down the eastward progression of the trough, maintaining unsettled weather and chances for rain through the end of the work week. Given potential for three days of rainy weather, latest ECMWF ensembles show 60 to 90% chance for at least 1 inch of rain for areas north of I-90 with a 50 to 70% chance for areas to the south. The probability for over 2 inches of rain through this period is much lower ranging 20 to 40% and confined mainly near and east of the Hudson River. This shows that despite the increasing confidence for a prolonged period of wet weather, widespread flooding appears unlikely but we will need to keep an eye out for more localized flooding issues which can occur in the presence of closed lows as shown in conceptual models from local research.

AVIATION /12Z MONDAY THROUGH FRIDAY/

Through 12z/Tuesday...VFR conditions are expected to continue again across all terminals through the TAF period. Current satellite imagery shows a band of high and mid clouds moving through from the southwest ahead of an approaching upper level trough just reaching KALB and KPSF. KGFL has already cleared this morning. KALB and KPSF should see some breaks this morning. KPOU will likely have lingering thicker mid level clouds through tomorrow. After a mostly clear start today, diurnally driven clouds will begin to develop with cigs around 5,000 ft to 7,000 ft after 17z. Hi-res guidance shows some light reflectivity in the vicinity of KPOU around 21z this evening however NBM guidance generally keeps the chance of showers less than 20%. With a dry airmass prevailing over the region today, confidence is low that rain will actually reach the ground if any showers do occur so this was not mentioned in the TAFs.

Winds continue to hold northwesterly through the TAF period with winds this morning 5 kt or less before picking back up by noon (15z- 18z) with speeds 5-10 kt and becoming gusty up to 25 kt by afternoon (18z). Winds then decrease into the evening again with speeds under 5 kt.

Outlook...

Tuesday Night: Low Operational Impact. NO SIG WX. Wednesday: High Operational Impact. Windy With Gusts To 30 kts. Definite SHRA. Wednesday Night: High Operational Impact. Breezy. Definite SHRA...TSRA. Thursday: High Operational Impact. Definite SHRA...TSRA. Thursday Night: Moderate Operational Impact. Chance of SHRA. Friday: Moderate Operational Impact. Chance of SHRA. Friday Night: Low Operational Impact. Slight Chance of SHRA. Saturday: Low Operational Impact. NO SIG WX.

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...Frost Advisory until 8 AM EDT this morning for NYZ038>041-043- 047-048-051-054-082>084. MA...None. VT...Frost Advisory until 8 AM EDT this morning for VTZ013-014.